The present invention relates to improvements in methods of and in apparatus for cyclically applying, monitoring and/or correcting adhesive patterns which serve to cause bands, strips, sheets or analogous commodities to adhere to each other and/or to other parts, especially in conjunction with the making and/or packing of rod-shaped smokers' products.
It is well known to coat cigarette paper, uniting bands and analogous sheet-like or strip-shaped commodities with an adhesive substance which causes the commodities to adhere to each other and/or to other parts, e.g., in connection with the making of filter cigarettes. For example, PCT/EP No. 98/06561 discloses a camera which is utilized as an optical monitoring unit and employs an objective connected to the camera body by an elongated optical conductor. The objective is installed at a location where it is not readily accessible and/or observable. The purpose of such camera is to ascertain whether or not one or more layers of an adhesive were properly applied to one or more sections of wrapping material.
U.S. Pat. No. 4,845,374 (granted Jul. 4, 1989 to White et al. for “METHOD AND APPARATUS FOR DETECTING THE DEPOSITION OF AN ADHESIVE ON A TRAVELLING WEB”) discloses a method of and an apparatus for intercepting and/or monitoring radiation being reflected by a travelling web in order to ascertain whether or not the web carries a substance or material. To this end, the web is exposed to diffuse light and the light being reflected by the web is monitored by a detector which is set up to ascertain the presence and/or the width of the adhesive-coated portions of the web on the basis of reflection of diffuse light at the coated surface of the web.